This invention relates to a landing adjustment system suitable for the installation of offshore marine structures such as offshore cities and the platforms of offshore oil fields and of offshore towers, for example, at the sea bed.
Of late, there has been a constant increase in population throughout the world. This increase in population presents grave problems in that the price of land for housing inevitably rises in a very small country such as Japan where the land area is extremely restricted in relation to the high density of population and in that the high population density tends to lead to a deterioration in the living environment which results in uncomfortable living conditions. In order to solve these problems, attempts have been made to effectively utilize offshore areas by constructing or installing offshore structures such as offshore cities and the platforms of offshore oil fields and towers at the sea bed.
Hithertofore, when offshore local districts or the platforms of offshore oil fields or towers are constructed or installed in offshore areas, the following three methods have been generally used: the first method is to construct an artificial island by reclamation, the second method is to float an offshore local district formed of a buoyant structure such as a pontoon on the sea and anchor the buoyant structure to the sea bed by suitable anchor means and the third method is to construct an offshore city on reinforced concrete or steel studs planted on the sea bed. However, since the artificial island involves reclamation, the laying out of the reclaimed island requires a colossal amount of investment and the depth of water places a limitation on the number of potential sites available for such artificial islands. The anchoring means for a buoyant offshore structure such as a pontoon requires frequent troublesome adjustment and the construction of the offshore city on reinforced concrete or steel studs encounters difficulties in terms of expensive foundation work. Thus, it has been found that each of the above mentioned conventional methods have their own inherent disadvantages.